The Synaxis of Michael & All Angels (est. 364) specifically names Michael, Gabriel, Raphael, Uriel, Selaphiel, Jehudiel, Barachiel, and Jeremiel (but not Leonardo or Donatello), but in fact honors all the bodiless hosts—we just don’t know all their names. (Michael’s secretary didn’t return my calls requesting a complete list.) The feast was first promulgated at the Council of Laodicea, which also published a list of Biblical books, condemned astrology, and called out for pizza more than once.
In ye olden dayes, feasts honoring the angels were celebrated on various days throughout the Christian world. In particular, “at the thermal baths of the Emperor Arcadius,” they were commemorated on November 8, which spread throughout the Christian East. The Latin rites keep the Feast of St. Michael and All Angels on September 29, referring to it colloquially as “Michaelmas,” for (what should be) obvious reasons.
Few angels are mentioned by name in the Scriptures. In post-biblical tradition, names were assigned to various unnamed angels; for example, Camael is the name given the angel who cast Adam and Eve out of the Garden, causing them to roam, and thus giving rise to the saying, “I’d walk a mile for Camael.” I could not find names for the angels who met with Abraham at Mamre, but we can be fairly certain none of them was named Rublev.
Traditionally the bodiless hosts (from “bodiless” meaning “having no body” and “hosts” meaning “armies”) are divided into three ranks of three ranks each, for a total of—well, I leave the math as an exercise for the reader. To wit: Top rank: Seraphim (six-winged), Cherubim (many-eyed), and Thrones (no number of parts specified). Middle rank: Dominions (teach subdual of sinful influences), Powers (assist in obedience fulfillment), and Authorities (protect from demonic temptations (e.g. chocolate, Bourbon whiskey)). Bottom rank: Principalities (instruct in rendering of honor to authority), Archangels (bear messages of great enlightenment (important note: not “The Enlightenment” which had nothing to do with angels), and (mere) Angels (bear messages of mundane enlightenment).
That Michael, from the next-to-last rank, should be in charge of all the bodiless hosts, is a mystery which my sources do not address. Perhaps it is because he is responsible for casting Satan out of heaven, and will lead the heavenly armies in the last battle (the real last battle, not the one in the Chronicles of Narnia, which is at best penultimate).
The Four Crowned Martyrs (d. 305 or 305) were nine different people who were martyred in groups of four and five, respectively. The group of four (Severus, Severianus, Carpophorus, and Victorinus) were soldier martyrs in in Rome. The group of five (Claudius, Castorius, Symphorian, Nicostratus, and Simplicius) were sculptors from Sirmium (in modern Serbia). They had an exemplary list of bona fides in the Angie’s List of the day, but when they refused to fulfill a commission by Emperor Diocletian to craft a statue of Aesculapius (despite having earlier carved a Victoria, Cupid, and Chariot of the Sun), and then refused to worship the gods, they were bound in lead caskets and tossed into the closest river (due to the well-documented difficulty of carrying lead coffins any great distance).
The commemorations of the two groups were combined by Pope Melchiades (reigned 311–314), due to the saints’ names not being all known at the time (they were later revealed to somebody in a vision). Their relics are said to be in many different places, including of all places England, where at least some of them were sent in 601. A Church of the Four Crowned Martyrs at Canterbury is mentioned by Bede* in his History.